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UPS ?

I have a 500VA Patriot (brand) UPS that has been working fine for many
many years.

I have a "mini" computer hooked to it, one that uses a "mini" PSU
mounted above the CPU which is also used to cool the CPU. It is very
loud, so I decided to re-case the machine and use a standard PSU and the
machine is working fine. I have a separate fan for the CPU and it's a
lot quieter.

The only problem is the UPS, when turned on, interrogates , then goes to
fault. I have many UPS's and just used another and it works fine.

The Patriot is more of an industrial grade UPS and may have more safety
features than the consumer grade APC unit I'm using.

The only thing I can think of is that the mobo is putting some kind of a
"leakage" condition on the PSU.

As soon as I turn the UPS on, the machine goes on too, without pushing
the power switch.

philo wrote:
I have a 500VA Patriot (brand) UPS that has been working fine for many
many years.

I have a "mini" computer hooked to it, one that uses a "mini" PSU
mounted above the CPU which is also used to cool the CPU. It is very
loud, so I decided to re-case the machine and use a standard PSU and the
machine is working fine. I have a separate fan for the CPU and it's a
lot quieter.

The only problem is the UPS, when turned on, interrogates , then goes to
fault. I have many UPS's and just used another and it works fine.

The Patriot is more of an industrial grade UPS and may have more safety
features than the consumer grade APC unit I'm using.

The only thing I can think of is that the mobo is putting some kind of a
"leakage" condition on the PSU.

As soon as I turn the UPS on, the machine goes on too, without pushing
the power switch.

Not a big deal just curious.

Ways to turn on the PC:

1) Busted power switch. Front button busted in the ON state.
But the circuits near the SuperI/O can be edge sensitive and
actually a busted switch like that won't turn on. On some PCs,
when you depress the button the PC doesn't come on, then when the
momentary button on the front is released, the PSU comes on
right after that. A modern motherboard is more likely to "behave
the complicated way".

2) The BIOS has a "Power Loss" setting, that can "Restore power to
previous state". If the PC was on when the AC went off, the PC will
try to turn on again, if the BIOS was set that way.

3) The motherboard will also switch on, if the Southbridge (PCH) is under
electrical stress. When an IDE cable on my machine was "half unplugged"
so only one half the pins touched, the machine turned itself on.
The problem corrected itself after I re-seated the IDE cable. This isn't
clever chip design, and it's just a side effect of the overloading
caused on the I/O pads.

*******

The Patriot would be a bad UPS, if it showed a fault code because of
a couple milliamps of leakage. The filter caps on the front end of the
ATX PSU, they "leak on purpose" into the Safety ground. This is by design.
And also by design, you can't run a PC off the power plug underneath
your shaving mirror in the bathroom (because the leakage detector there
is not intended for that level of leakage).

Components C2 and C3 here, are examples of capacitors that leak 60Hz
from the AC rails, back into Safety ground. They do it this way, to
filter switching noise currents so they don't go back into rail. The
level of current flow is a function of the capacitor value, and the
capacitor value has some tolerance on it (could be -80%, +20% for example).

Now, if the supply was actually defective, and the magnitude of the
Safety current flow was much larger, then the Patriot would be
a Good UPS :-) It's all a matter of interpretation as to whether
any Fault detection is too sensitive.

I would take my cheater cord, with the three exposed wire loops
sticking out of it, and put my clamp-on AC ammeter on the Safety
ground wire, and check the current flow level when powered from
the wall. My meter isn't sensitive enough to detect a normal
level of current flow (1 or 2 mA), but if the PSU was damaged,
and more than normal current went into Safety Ground, I could
detect that. The clamp-on ammeter means I'm not going to come
in contact with the circuit while I work.

I would prefer not to mess around with "opening" the Safety Ground
and trying to measure the current flow the old fashioned way with my
Simpson. That's an option if it's all you've got.

The PSU will work, even if the Safety Ground is open. However,
when you touch the chassis of the PSU under those conditions,
you'll get a (non-fatal) shock. The leakage level is intended
to be "safe but annoying" for dry hands. The leakage level is
too much for taking the ATX PSU into the bath tub with you.
Anything could happen then.

If you own an outlet tester, you could also test
that the outlet the Patriot is connected to, shows a
"good" code. At times, those can be hard to find,
and in the style you might like. I managed to get one
at a local hardware store, but I had to go all over town
to find it. I know I have another one around here... somewhere.
These can use things like neon bulbs to detect reverse
hot and neutral, missing Safety ground and so on. There's
usually a table of all the codes to help you interpret how
the outlet wiring is screwed up.

1) Busted power switch. Front button busted in the ON state.
¬*¬* But the circuits near the SuperI/O can be edge sensitive and
¬*¬* actually a busted switch like that won't turn on. On some PCs,
¬*¬* when you depress the button the PC doesn't come on, then when the
¬*¬* momentary button on the front is released, the PSU comes on
¬*¬* right after that. A modern motherboard is more likely to "behave
¬*¬* the complicated way".

2) The BIOS has a "Power Loss" setting, that can "Restore power to
¬*¬* previous state". If the PC was on when the AC went off, the PC will
¬*¬* try to turn on again, if the BIOS was set that way.

3) The motherboard will also switch on, if the Southbridge (PCH) is under
¬*¬* electrical stress. When an IDE cable on my machine was "half unplugged"
¬*¬* so only one half the pins touched, the machine turned itself on.
¬*¬* The problem corrected itself after I re-seated the IDE cable. This
isn't
¬*¬* clever chip design, and it's just a side effect of the overloading
¬*¬* caused on the I/O pads.

*******

The Patriot would be a bad UPS, if it showed a fault code because of
a couple milliamps of leakage. The filter caps on the front end of the
ATX PSU, they "leak on purpose" into the Safety ground. This is by design.
And also by design, you can't run a PC off the power plug underneath
your shaving mirror in the bathroom (because the leakage detector there
is not intended for that level of leakage).

Components C2 and C3 here, are examples of capacitors that leak 60Hz
from the AC rails, back into Safety ground. They do it this way, to
filter switching noise currents so they don't go back into rail. The
level of current flow is a function of the capacitor value, and the
capacitor value has some tolerance on it (could be -80%, +20% for example).

Now, if the supply was actually defective, and the magnitude of the
Safety current flow was much larger, then the Patriot would be
a Good UPS :-) It's all a matter of interpretation as to whether
any Fault detection is too sensitive.

I would take my cheater cord, with the three exposed wire loops
sticking out of it, and put my clamp-on AC ammeter on the Safety
ground wire, and check the current flow level when powered from
the wall. My meter isn't sensitive enough to detect a normal
level of current flow (1 or 2 mA), but if the PSU was damaged,
and more than normal current went into Safety Ground, I could
detect that. The clamp-on ammeter means I'm not going to come
in contact with the circuit while I work.

I would prefer not to mess around with "opening" the Safety Ground
and trying to measure the current flow the old fashioned way with my
Simpson. That's an option if it's all you've got.

The PSU will work, even if the Safety Ground is open. However,
when you touch the chassis of the PSU under those conditions,
you'll get a (non-fatal) shock. The leakage level is intended
to be "safe but annoying" for dry hands. The leakage level is
too much for taking the ATX PSU into the bath tub with you.
Anything could happen then.

If you own an outlet tester, you could also test
that the outlet the Patriot is connected to, shows a
"good" code. At times, those can be hard to find,
and in the style you might like. I managed to get one
at a local hardware store, but I had to go all over town
to find it. I know I have another one around here... somewhere.
These can use things like neon bulbs to detect reverse
hot and neutral, missing Safety ground and so on. There's
usually a table of all the codes to help you interpret how
the outlet wiring is screwed up.

¬*¬* Paul

Thanks Paul.

It seems to be something to do with the mobo's behavior with a PSU other
than the original.

The mobo has a 20 pin power connection and the original supply had a 24
pin connection (with the 4 pin connector left dangling of course.)

I replaced it with a simple 20 pin PSU

I know that there the 20 pins of a 24 pin PSU are somehow a bit
different than that of a straight 20 pin PSU because when I test 24 pin
supplies with my 20 pin tester, one of the red warning lights goes on
even though the supply is good.

It seems to be something to do with the mobo's behavior with a PSU other
than the original.

The mobo has a 20 pin power connection and the original supply had a 24
pin connection (with the 4 pin connector left dangling of course.)

I replaced it with a simple 20 pin PSU

I know that there the 20 pins of a 24 pin PSU are somehow a bit
different than that of a straight 20 pin PSU because when I test 24 pin
supplies with my 20 pin tester, one of the red warning lights goes on
even though the supply is good.

The four leftover pins on the 24 pin are for "ampacity". You might not
find that in your dictionary, and some staff at work introduced me
to the (apparently made up) word.

There is no functional difference as such between 20 and 24 pins.
The 24 pins, the actual useful benefit, is the additional yellow
+12V wire, which was badly needed. That raises the current available
for PCIe slots from 6A to 12A. Before the 24 pin came along, some
companies were putting a 4 pin Molex on the motherboard, to carry
a bit more current for +12V.

There are two tables here, you can use to compare a 20 pin to
a 24 pin. The difference, the extra four pins, look like this.

There are already a fair number of 3.3V, 5V, and Ground wires
so adding one more of each isn't as big an improvement, as that
Yellow wire for +12V is.

The worst card for slot power, was a 6600 video card, with 4.2A
of 12v slot power. Two of those would exceed the conservative 6A
limit for the single Yellow wire on the 20 pin. You could safely
run two 6600 cards on a 24 pin connector, as the 12A available,
exceeded the 8.4A load.

When you buy a $1000 video card, those only draw around 2A from
the slot. It's the mid-range cards, the one without a PCIe power
connector on the end, that push towards the slot limit of 12V @ 5A max.

It's really hard to guess where the 3.3V and 5V current flow
levels are today. But you'll notice that the "gigantic" modern
80+ supplies only offer 20A on 3.3V and 5V. And it is hard to
get a supply with more (there are traditional design PSUs that
go up to 40A on the low rails).

Some video cards have used as much as 3A on the 3.3V, so two video
cards would be 6A out of 20A. And the chipset is pretty thirsty
and could well be running from the wrong rail as well. There will
be some things that can run directly from 3.3V. And a lot of lower
voltages (1.2, 1.5, 1.0V) that you could run off 12V if you had the
ampacity to do it. Switching regulators (like the switching supply for
the DIMMs) get less efficient at lower voltages (but that's never
stopped anyone in the past).

With the "sleeved" cables of modern supplies, I can't get my
ammeter jaws around stuff, to characterize my newer machines.
And the new machine, the heatsink is so big, I can't even get
my hands inside to seat half of the DIMMs, and have to snap
them into place with a sort of dowel to press down on them.
Not the nicest place to be doing power testing. No room
for anything. And spinning fan blades to nick me if I get
too adventurous (VCore has a fan on it now).

It seems to be something to do with the mobo's behavior with a PSU
other than the original.

The mobo has a 20 pin power connection and the original supply had a
24 pin connection (with the 4 pin connector left dangling of course.)

I replaced it with a simple 20 pin PSU

I know that there the 20 pins of a 24 pin PSU are somehow a bit
different than that of a straight 20 pin PSU because when I test 24
pin supplies with my 20 pin tester, one of the red warning lights goes
on even though the supply is good.

The four leftover pins on the 24 pin are for "ampacity". You might not
find that in your dictionary, and some staff at work introduced me
to the (apparently made up) word.

There is no functional difference as such between 20 and 24 pins.
The 24 pins, the actual useful benefit, is the additional yellow
+12V wire, which was badly needed. That raises the current available
for PCIe slots from 6A to 12A. Before the 24 pin came along, some
companies were putting a 4 pin Molex on the motherboard, to carry
a bit more current for +12V.

There are two tables here, you can use to compare a 20 pin to
a 24 pin. The difference, the extra four pins, look like this.

There are already a fair number of 3.3V, 5V, and Ground wires
so adding one more of each isn't as big an improvement, as that
Yellow wire for +12V is.

The worst card for slot power, was a 6600 video card, with 4.2A
of 12v slot power. Two of those would exceed the conservative 6A
limit for the single Yellow wire on the 20 pin. You could safely
run two 6600 cards on a 24 pin connector, as the 12A available,
exceeded the 8.4A load.

When you buy a $1000 video card, those only draw around 2A from
the slot. It's the mid-range cards, the one without a PCIe power
connector on the end, that push towards the slot limit of 12V @ 5A max.

It's really hard to guess where the 3.3V and 5V current flow
levels are today. But you'll notice that the "gigantic" modern
80+ supplies only offer 20A on 3.3V and 5V. And it is hard to
get a supply with more (there are traditional design PSUs that
go up to 40A on the low rails).

Some video cards have used as much as 3A on the 3.3V, so two video
cards would be 6A out of 20A.¬* And the chipset is pretty thirsty
and could well be running from the wrong rail as well. There will
be some things that can run directly from 3.3V. And a lot of lower
voltages (1.2, 1.5, 1.0V) that you could run off 12V if you had the
ampacity to do it. Switching regulators (like the switching supply for
the DIMMs) get less efficient at lower voltages (but that's never
stopped anyone in the past).

With the "sleeved" cables of modern supplies, I can't get my
ammeter jaws around stuff, to characterize my newer machines.
And the new machine, the heatsink is so big, I can't even get
my hands inside to seat half of the DIMMs, and have to snap
them into place with a sort of dowel to press down on them.
Not the nicest place to be doing power testing. No room
for anything. And spinning fan blades to nick me if I get
too adventurous (VCore has a fan on it now).

¬*¬* Paul

I am familiar with the portmanteau"ampacity" but shy away from using the
term.

It too much reminds me of laymen who use the term "amperage" rather
than "current."

At any rate, I decided to have a look at all the spare power supplies I
have in my workshop and the older 20 pin supplies have a white (-5v)
wire at pin 18.

My tester which is evidently ancient gives all green lights on those
supplies.

I have some newer 20 pin supplies which do not have that white wire
which corresponds to the "missing" wire at pin 20 on the 24 pin supplies.

My tester gives an over-all fault (red) for those supplies but all other
green lights are lit up but one.

Now that I have the machine all put back together and working I don't
think I'll fool with it anymore, but one of these days when I get a
chance I'll see what can cause a fault on that old Patriot UPS I have.

Though I always use 24 pin supplies with 24 pin motherboards, in this
case, since the mobo was just 20 pin, I figured it would be a good way
to use up one of my old, 20 pin supplies.

It seems to be something to do with the mobo's behavior with a PSU
other than the original.

The mobo has a 20 pin power connection and the original supply had a
24 pin connection (with the 4 pin connector left dangling of course.)

I replaced it with a simple 20 pin PSU

I know that there the 20 pins of a 24 pin PSU are somehow a bit
different than that of a straight 20 pin PSU because when I test 24
pin supplies with my 20 pin tester, one of the red warning lights
goes on even though the supply is good.

The four leftover pins on the 24 pin are for "ampacity". You might not
find that in your dictionary, and some staff at work introduced me
to the (apparently made up) word.

There is no functional difference as such between 20 and 24 pins.
The 24 pins, the actual useful benefit, is the additional yellow
+12V wire, which was badly needed. That raises the current available
for PCIe slots from 6A to 12A. Before the 24 pin came along, some
companies were putting a 4 pin Molex on the motherboard, to carry
a bit more current for +12V.

There are two tables here, you can use to compare a 20 pin to
a 24 pin. The difference, the extra four pins, look like this.

There are already a fair number of 3.3V, 5V, and Ground wires
so adding one more of each isn't as big an improvement, as that
Yellow wire for +12V is.

The worst card for slot power, was a 6600 video card, with 4.2A
of 12v slot power. Two of those would exceed the conservative 6A
limit for the single Yellow wire on the 20 pin. You could safely
run two 6600 cards on a 24 pin connector, as the 12A available,
exceeded the 8.4A load.

When you buy a $1000 video card, those only draw around 2A from
the slot. It's the mid-range cards, the one without a PCIe power
connector on the end, that push towards the slot limit of 12V @ 5A max.

It's really hard to guess where the 3.3V and 5V current flow
levels are today. But you'll notice that the "gigantic" modern
80+ supplies only offer 20A on 3.3V and 5V. And it is hard to
get a supply with more (there are traditional design PSUs that
go up to 40A on the low rails).

Some video cards have used as much as 3A on the 3.3V, so two video
cards would be 6A out of 20A. And the chipset is pretty thirsty
and could well be running from the wrong rail as well. There will
be some things that can run directly from 3.3V. And a lot of lower
voltages (1.2, 1.5, 1.0V) that you could run off 12V if you had the
ampacity to do it. Switching regulators (like the switching supply for
the DIMMs) get less efficient at lower voltages (but that's never
stopped anyone in the past).

With the "sleeved" cables of modern supplies, I can't get my
ammeter jaws around stuff, to characterize my newer machines.
And the new machine, the heatsink is so big, I can't even get
my hands inside to seat half of the DIMMs, and have to snap
them into place with a sort of dowel to press down on them.
Not the nicest place to be doing power testing. No room
for anything. And spinning fan blades to nick me if I get
too adventurous (VCore has a fan on it now).

Paul

I am familiar with the portmanteau"ampacity" but shy away from using the
term.

It too much reminds me of laymen who use the term "amperage" rather
than "current."

At any rate, I decided to have a look at all the spare power supplies I
have in my workshop and the older 20 pin supplies have a white (-5v)
wire at pin 18.

My tester which is evidently ancient gives all green lights on those
supplies.

I have some newer 20 pin supplies which do not have that white wire
which corresponds to the "missing" wire at pin 20 on the 24 pin supplies.

My tester gives an over-all fault (red) for those supplies but all other
green lights are lit up but one.

Now that I have the machine all put back together and working I don't
think I'll fool with it anymore, but one of these days when I get a
chance I'll see what can cause a fault on that old Patriot UPS I have.

Though I always use 24 pin supplies with 24 pin motherboards, in this
case, since the mobo was just 20 pin, I figured it would be a good way
to use up one of my old, 20 pin supplies.

The need for -5V was removed from the standard years ago. The
dates can be a bit deceiving, as the industry could see the writing
on the wall, before it became official. So even though spec 1.3
says "year 2003" on it, mobo designers stopped using -5V before that.

My P2B-S (year 2000???) has a voltage monitor input for -5V, but
no circuitry on the motherboard uses -5V. The two RS232 chips use
-12V for the bipolar RS232 output swing. Even my P4C800-E Deluxe
(a P4 mobo) didn't use a Maxim "pumped" RS232 and the TI 75232
chip on that one continued to use -12V. That's about the only
reason to still have -12V. You can use -12V for op amp circuits,
or maybe for a little 2W power amp for passive speakers, but other
than that, there aren't a lot of excuses for -12V. And the -5V
back in the day, was used for digital chips. And all those chips
stopped using -5V. For maybe a year or two, you could build a
design purely out of +5V circuitry, but then the industry moved
on and new voltage requirements were introduced. Today, a Southbridge
could have as many as five rails on it (with many of the voltages
made by circuits on the motherboard). Even a NIC is dual rail, with
maybe 3.3V for digital I/O signals, but 1.8V or lower to power
the core circuits inside the chip.

Core logic today can run off 1.0V. They even make op amps that
run off voltages like that. I don't expect they'll go too much
lower. The 200W video card you own, the core of that runs at
around 1.0V. And the voltage regulator has to provide 200A
of current, and the copper planes in the video card have to
be able to withstand a 200A flow.

*******

You might notice that one pin on the ATX PSU, has two wires.
That's for remote sense of 3.3V output. That remote sense leads
to tighter regulation on the 3.3V output. To make the ATX PSU
supply 1.0V to the motherboard say, you'd need to run the
remote sense right to the load, to do a good job. This is one
reason that power supplies will not be making voltages lower
than the 3.3V they make today. Tolerances. And the cabling
that results from doing it that way, would be quite inconvenient.

My tester gives an over-all fault (red) for those supplies but all
other green lights are lit up but one.

Now that I have the machine all put back together and working I don't
think I'll fool with it anymore, but one of these days when I get a
*

My P2B-S (year 2000???) has a voltage monitor input for -5V, but
no circuitry on the motherboard uses -5V. The two RS232 chips use
-12V for the bipolar RS232 output swing. Even my P4C800-E Deluxe
(a P4 mobo) didn't use a Maxim "pumped" RS232 and the TI 75232
chip on that one continued to use -12V. That's about the only
reason to still have -12V. You can use -12V for op amp circuits,
or maybe for a little 2W power amp for passive speakers, but other
than that, there aren't a lot of excuses for -12V. And the -5V
back in the day, was used for digital chips. And all those chips
stopped using -5V. For maybe a year or two, you could build a
design purely out of +5V circuitry, but then the industry moved
on and new voltage requirements were introduced. Today, a Southbridge
could have as many as five rails on it (with many of the voltages
made by circuits on the motherboard). Even a NIC is dual rail, with
maybe 3.3V for digital I/O signals, but 1.8V or lower to power
the core circuits inside the chip.

Core logic today can run off 1.0V. They even make op amps that
run off voltages like that. I don't expect they'll go too much
lower. The 200W video card you own, the core of that runs at
around 1.0V. And the voltage regulator has to provide 200A
of current, and the copper planes in the video card have to
be able to withstand a 200A flow.

*******

You might notice that one pin on the ATX PSU, has two wires.
That's for remote sense of 3.3V output. That remote sense leads
to tighter regulation on the 3.3V output. To make the ATX PSU
supply 1.0V to the motherboard say, you'd need to run the
remote sense right to the load, to do a good job. This is one
reason that power supplies will not be making voltages lower
than the 3.3V they make today. Tolerances. And the cabling
that results from doing it that way, would be quite inconvenient.

¬*¬* Paul

And then of course there are those old Dell non-standard ATX supplies.

I suppose I could probably get rid of the few I have left.

Anyway as always, I think you for your extreme knowledge .

BTW: I still do computer repair work and this young woman brought over a
machine she uses for video editing. It quit on her when her boyfriend
who built it was out of town.

The problem was simply that the power wire fell off the SSD.

It had a relatively small case and the PSU wires were long and bulky.

I had to re-route and tie down the cables ,

The last machine I built for myself, the one I'm using now has a mini
motherboard and a huge case (22" high)